生物滞留系统植物筛选与综合评价

为科学筛选出生物滞留系统中能有效去除多种污染物的最佳植物,选取10种重庆市本土植物构建雨水生物滞留系统,以控制山地城市道路雨水径流污染;并采用反向传播动态神经网络(BP-DNN)技术构建了基于多目标污染物的综合评价模型,对所有生物滞留系统进行应用评价。结果表明:植物可有效去除有机物和营养物等多种污染物,但存在差异性;植被种类对COD的去除影响显著,其中,风车草去除效能最佳,而千屈菜最差;植物的栽种可有效提高系统对NH_4~+-N的去除率,但差异性并不显著,同时,部分植物能在一定程度上提高系统对NO_3~--N的去除,但不稳定;植物的栽种能有效提高系统的除氮性能,选用风车草时系统除氮性能最佳,TN去除率可达64.30%～86.82%,而植物的栽种对TSS和TP的去除无显著影响。在综合评价的10种植物中,风车草和美人蕉为生物滞留系统的最佳植物。     

漂浮植物塘协同处理农村分散生活污水研究

通过实验考察了漂浮植物塘对经模拟化粪池简易处理的农村分散生活污水的深度净化效果，结果表明：水葫芦、大薸、聚草塘对上述污水均具有良好的净化效果，水葫芦塘对TP的去除效果最好，大薸塘对TN和NH⁺₄-N的去除效果最好。当水力停留时间为20 d时，3种漂浮植物塘的出水污染物含量可低于GB/T 18921-2002观赏性景观环境用水河道类标准。在南方农村宅沟园河内种植漂浮植物是构建农村实用生活污水收集处理系统、控制农村生活污水对河道污染的一种有效措施。     

表面活性剂强化植物-微生物联合修复双对氯苯基三氯乙烷污染土壤研究

通过实验对比研究植物(油菜)修复、微生物(甲基营养型芽孢杆菌(Bacillus methylotrophicus))修复、表面活性剂(聚氧乙烯山梨醇酐单硬脂酸酯(Tween 60))以及联合修复技术对双对氯苯基三氯乙烷(DDT)污染土壤的DDT去除效果。结果表明:以植物-表面活性剂-微生物共同作用下的DDT去除效果最好,土壤DDT去除率达到52.44%;油菜不仅可有效去除土壤中残留的DDT,同时只在地下部分对DDT进行了微量吸收,但没有进行转运,防止了农药在油菜可食部位的累积,保障了食品与生产安全。     

3种水生植物对富营养化水质的净化性能比较

选择芦苇、狐尾藻、菖蒲3种水生植物净化富营养化水体,考察了不同水生植物及组合对富营养化水体中硝酸盐氮、氨氮、TN、TP、COD、BOD5的去除效果。结果表明,菖蒲对氮、磷的去除效果明显优于芦苇和狐尾藻,狐尾藻在COD的去除上表现出一定的优势,而芦苇对BOD5的去除效果最加。在植物组合处理中,菖蒲+狐尾藻组合对氮、BOD5去除效果最佳,处理28d后,TN、BOD5去除率分别达80%、57%,芦苇+菖蒲组合对TP、COD去除效果优于其他组合,处理28d后,TP、COD去除率分别达87%、72%;处理过程中,狐尾藻生物量增长最多,且对芦苇、菖蒲具有明显的抑制作用,是3种植物中的优势物种。综合考虑水质净化效果及植物生长状况,菖蒲和芦苇可作为富营养化水体的净化植物,而狐尾藻则应该谨慎使用。     

人工湿地中基质与植物对污染物去除效率的影响

针对太湖五里湖富营养化水体，采用中试规模的人工湿地现场实验开展了不同基质、不同植物的污染物去除效果研究。基质采用炉渣和沸石2种，在一个湿地池种植单一植物茭白，另一个湿地池种植鸢尾＋菖蒲混合植物，同时构建了无植物的对照组湿地。研究表明：（1）在运行初期，沸石和炉渣2种基质对TN、TP的去除率差异为12.5%和12.6%，吸附饱和后，2种基质对TN和TP的去除率差异缩小为3.2%和6.1%，从长期运行来看，炉渣和沸石2种基质在人工湿地中的去除效率差异将减小；（2）茭白单一植物湿地对污染物的去除率与鸢尾＋菖蒲混合植物湿地对污染物的去除率两者之间差异不大；（3）人工湿地种植植物后对TN、TP的去除率比无植物状态时分别高出13.6%和19.5%，植物在人工湿地中对污染物的去除发挥了重要作用；（4）在本试验条件下，茭白吸收所去除的氮数量为湿地氮总去除量的8.95%，茭白吸收去除磷的数量为湿地磷总去除量的20.16%，在人工湿地中，茭白吸收对磷的去除效率比对氮的去除效率高。     

3种浮床植物系统对富营养化水体净化效果研究

研究了风车草(Cyperus alternifolius)、菖蒲(Acorus calamus)和富贵竹(Dracaena sanderiana)3种浮床植物系统对富营养化水体净化效果,试验共持续35 d。结果表明,在水温24～30℃条件下,风车草和菖蒲生长良好,生物量大,而富贵竹生长较差,生物量增加少;3种植物对NH_4~+-N的去除率分别为76.8%、85.5%和53.6%,对TN的去除率分别为69.1%、66.2%和54.4%,对TP的去除率分别为76.9%、84.6%和61.5%,对PO_4~(3-)-的去除率分别为91.7%、91.7%和75%,对真实色度有明显的去除效果;3种植物对氮磷和真实色度去除效果与对照之间均达到显著差异(P0.05),自然沉淀是浊度去除的主要原因,植物吸收同化作用是NH_4~+-N去除的主要途径,植物吸收是溶解性磷去除的主要途径。试验表明,风车草和菖蒲对富营养化水体中氮磷和真实色度有较好的去除效果,可作为富营养化水体治理的优良物种而推广使用。     

蚯蚓生态滤池中蚯蚓与植物对污水净化的作用评估

构建具有不同蚯蚓和植物配置的4个单级蚯蚓生态滤池,依次编号为A(无蚯蚓无植物)、B(有蚯蚓无植物)、C(有蚯蚓栽种芦苇)和D(有蚯蚓栽种水生鸢尾)。通过比较4个滤池在6个月实验期间对化学需氧量(COD)和总氮(TN)的去除效率,系统分析蚯蚓和植物对滤池去除污染物的影响。实验分2个阶段进行:5月上旬至9月上旬,滤池进水碳氮比恒定为6;9月中旬至11月中旬,滤池每周进水碳氮比交替为3、6、9。研究结果表明,蚯蚓对滤池去除COD有一定的促进作用,且作用强度显著受到进水碳氮比的影响。植物的存在与种类对滤池去除COD效率没有显著影响。蚯蚓和植物对滤池的TN去除效率都没有显著影响。滤池进水的碳氮比是显著影响滤池去除TN效率的主要因素。     

植物及其根系分泌物对污水净化效果的影响

为了弄清不同植物对污水的净化效率以及其根系分泌物对污水净化效果的影响,对植物根系分泌物与脱氮及COD去除之间的关系进行了研究。结果表明,在净化时间相同的情况下,茭白（Zizania cadaciflora）对污水COD的去除效果要好于美人蕉（Canna generalis）,美人蕉对污水TN的去除率要高于茭白,系统中N去除主要依靠硝化反硝化脱氮;美人蕉根系比茭白根系能分泌更多的溶解有机碳（DOC）,这些可溶性的有机碳可以为污水中微生物提供碳源,有利于氮的反硝化去除,但同时也会增加出水COD的浓度。而茭白比美人蕉具有更强的硝化能力,可促进其硝化反硝化作用。     

生态浮岛复合技术净化黑臭河道废水的实验研究

以宁波市前塘河水作为实验水体,采用不同水生植物及组合、生态浮岛复合技术净化水中污染物。经过14d的水培实验发现,沉水植物COD去除能力高于浮水植物和挺水植物;水生植物组合对COD的去除率相对较低,但去除率仍不低于79.9%。水生植物组合对氨氮的去除效果好于单一种类植物。沉水植物去除总磷的效果好于浮水植物与挺水植物,不同水生植物及组合的总磷去除率均大于44.0%。生态浮岛复合技术对废水中污染物的去除能力较强,实验10d时COD、氨氮、总磷去除率分别为97.1%、100.0%、73.8%。由此可见,水生植物和微生物的协同净化作用使生态浮岛复合技术对污染物的降解效果非常显著。     

观赏植物对沼液的净化效果

为研究观赏植物对沼液的净化能力,以滴水观音、水仙、红掌、白掌、万年青、绿萝、风信子为研究对象,通过沼液水培实验,对比分析了不同植物的生长特性及其对污染物的去除效果。结果表明,万年青、白掌、红掌和滴水观音的相对生长量和适应能力明显优于其他植物;随着处理时间的延长,大部分植物对COD的去除率呈增加趋势,最终达80%左右;在处理时间为7 d时,红掌、白掌和万年青对TN的去除率均达到80%以上;7种植物对沼液中TP的去除率在整个水培期间均未超过60%。各植物对污染物的去除效果均显著优于空白组(p0.05),且不同种类的植物之间差异明显(p0.05)。实验表明,万年青、红掌、白掌可作为处理沼液的备选观赏植物。     

Global water crisis: the major issue of the 21st century,a growing and explosive problem

The authors explore what is considered to be the emerging issue of the 21st century, shortages of water. It is expected that the Netherlands, which is entirely dependent on water from other countries, will be in an extremely vulnerable position. The quantity of fresh water is limited. Contamination of water reduces water quality and availability. Many World Bank projects focus on management of the water supply for sanitation, irrigation, hydroelectric power, and construction of dikes in order to prevent flooding. The World Bank concludes that everyone worldwide must acknowledge that fresh water is a scarce natural resource. The Action Plan, Agenda 21, of the UN Rio Conference emphasized the importance of the widespread shortage, gradual destruction, and increased pollution of fresh water reserves. The four major world problems with fresh water are 1) shortages of renewable supplies, 2) unequal distribution of supplies, 3) problems of water quality and health, and 4) disastrous effects of unrestrained construction of dams and reservoirs. Only 2.5% of the total amount of water on earth is fresh water, of which 69.4% is in the form of ice, snow, or permafrost and most of the remainder is ground water. Fresh water in lakes and rivers is only about 1% of fresh water available on earth. Most of the precipitation that falls on land every year is lost through evaporation. 45,000 sq. km is the absolute maximum available annually. Distribution of water among industry, agriculture, and households varies by country. Arid regions constitute about 33% of Europe, 60% of Asia, 85% of Africa, and most of Australia and western North America. 14% of countries are at or under the poverty line of water availability, 37% have dangerously dry conditions, 14% have average levels, and 35% have ample supplies. Examples of water management are given for the Amazon River, the Euphrates and Tigris, the Aral Sea, and the Rhine River Basin. It is estimated that the world supply of fresh water would meet the needs of 4.5-9.0 billion people.     

Phototransformation of methabenthiazuron in the presence of nitrate and nitrite ions

The influence of nitrate and nitrite ions on the degradation of methabenzthiazuron upon irradiation using artificial solar light has been investigated. The rate of degradation of methabenzthiazuron (1 microM) was accelerated by NO3- (0.1 mM) by a factor of 10. The irradiation of methabenzthiazuron (0.1 mM) in the presence of NO3- (1 mM) or NO2- (0.1 mM) yielded numerous intermediary photoproducts. Mineralization was achieved after prolonged exposure. Some were identified with the help of LC-ESI-MS and flow injection APCI-MS techniques. Both oxidations of the aromatic ring and of the urea chain were observed. The former started by hydroxylation of the ring. Further oxidation of the ring led to cleavage of the benzenic ring with formation of dialdehydic, diacidic and anhydric compounds. Complete removal of the lateral urea chain took place subsequently to demethylation of the terminal methyl group and loss of the CO-NH2 group. Nitration was a minor process. This work shows that the photodegradation of methabenzthiazuron in the presence of nitrate or nitrite ions is highly non-specific.     

Molluscicidal activity of Ferula asafoetida, Syzygium aromaticum and Carum carvi and their active components against the snail Lymnaea acuminata

The molluscicidal activity of dried root latex powder of Ferula asafoetida, flower-bud powder of Syzygium aromaticum and seed powder of Carum carvi against the snail Lymnaea acuminata was studied. The molluscicidal activity of all the three plant products was found to be both time and concentration dependent. The toxicity of S. aromaticum flower-bud powder (96 h LC(50):51.98 mg/l) was more pronounced than that of root latex powder of F. asafoetida (96 h LC(50):82.71 mg/l) and seed powder of C. carvi (96 h LC(50):140.58 mg/l). Ethanol extract was more toxic than other organic extracts. The ethanol extract of S. aromaticum (24h LC(50):83.53 mg/l) was more effective than that of F. asafoetida (24h LC(50):132.31 mg/l) and C. carvi (24h LC(50):130.61 mg/l) in killing the test animals. The 96 h LC(50) of column purified fraction of seed powder of C. carvi was 5.40 mg/l whereas those of flower-bud powder of S. aromaticum and dried root latex powder of F. asafoetida were 7.87 and 9.67 mg/l, respectively. The product of F. asafoetida, S. aromaticum and C. carvi may be used as potent molluscicides.     

Copper and zinc retention by an organically amended soil

This paper describes changes in retention of Cu and Zn in laboratory experiments by a sandy soil that had been amended in the field with different composted wastes. The amounts of the metals retained increased as a result of the amendments, especially after two years. Desorption of the sorbed metals was always negligible, regardless of the treatment. The proportion of Cu retained was considerably higher than that of Zn, suggesting a higher affinity of the soil for the former. The greater sorption in the amended soils indicates a build-up of fresh sites for metal retention.The use of 'log(activity) vs. pH' plots showed that the nature of the surfaces retaining metals on the untreated and amended soils is different. At comparable pH values, the amended soils gave higher solution metal concentrations. Some of the possible environmental consequences of the use of these amendments for remediation purposes are discussed.     

Physico-chemical versus microbial release of c-atrazine bound residues from a loamy clay soil incubated in laboratory microcosms

A loamy clay soil containing unextractable ¹⁴C-ring labeled atrazine residues was incubated in microcosms under abiotic and biotic conditions. The mineralization activity of the soil microflora was evaluated by the release of total CO₂ and ¹⁴C0₂. After 63 days of sample incubation the total organic carbon mineralization was of 1.71%, that of ¹⁴C-residues was of 0.72% of the initial radioactivity. No direct relationship was established between the mineralization of atrazine residues and the global mineralization. The contribution of soil microorganisms in the release of ¹⁴C-residues was weak. The availability of non-extractable residues was mainly controlled by physico-chemical factors. The low value of the reextractability rate and the distribution of bound residues during the soil sample incubation shown the active role of organic matter in detoxification procedure. Ninety percent of the residues remained bound after 63 days of incubation and were thus, potentially available without biocide activity.

The fractionation of soil organic matter allowed to specify the distribution of bound residues within the organic compartments. After a long-stay of pesticides in soils, approximately 65% of bound residues were associated with humin.     

Decolorization of direct dyes by salt fractionated turnip proteins enhanced in the presence of hydrogen peroxide and redox mediators

The present paper demonstrates the effect of salt fractionated turnip (Brassica rapa) proteins on the decolorization of direct dyes, used in textile industry, in the presence of various redox mediators. The rate and extent of decolorization of dyes was significantly enhanced by the presence of different types of redox mediators. Six out of 10 investigated compounds have shown their potential in enhancing the decolorization of direct dyes. The performance was evaluated at different concentrations of mediator and enzyme. The efficiency of each natural mediator depends on the type of dye treated. The decolorization of all tested direct dyes was maximum in the presence of 0.6mM redox mediator at pH 5.5 and 30 degrees C. Complex mixtures of dyes were also maximally decolorized in the presence of 0.6mM redox mediator (1-hydroxybenzotriazole/violuric acid). In order to examine the operational stability of the enzyme preparation, the enzyme was exploited for the decolorization of mixtures of dyes for different times in a stirred batch process. There was no further change in decolorization of an individual dye or their mixtures after 60 min; the enzyme caused more than 80% decolorization of all dyes in the presence of 1-hydroxybenzotriazole/violuric acid. However, there was no desirable increase in dye decolorization of the mixtures on overnight stay. Total organic carbon analysis of treated dyes or their mixtures showed that these results were quite comparable to the loss of color from solutions. However, the treatment of such polluted water in the presence of redox mediators caused the formation of insoluble precipitate, which could be removed by the process of centrifugation. The results suggested that catalyzed oxidative coupling reactions might be important for natural transformation pathways for dyes and indicate their potential use as an efficient means for removal of dyes color from waters and wastewaters.     

Essential interactions between Thiobacillus ferrooxidans and heterotrophic microorganisms during a wastewater sludge bioleaching process

The stimulating effect of heterotrophic microorganisms was investigated on the growth and on the ferrous iron oxidation of Thiobacillus ferrooxidans in synthetic media and in wastewater sludge. The addition of a sediment. Rhodotorula rubra isolate or a strain of T. acidophilus on two-layer agarose-gelled medium doubled the plating efficiency of T. ferrooxidans. In liquid cultures, R. rubra had a slight but significant effect on the growth rate of T. ferrooxidans. Moreover, the yeast allowed a faster initiation of the ferrous iron oxidation and acidification by T. ferrooxidans. In the bioleaching process, the co-culture of T. ferrooxidans with R. rubra or with the indigenous microbial assemblage from sludge was shown to be essential since the pure culture of T. ferrooxidans failed to oxidize ferrous iron and to acidify wastewater sludge. These results emphasize the importance of active heterotrophic microorganisms in the metal bioleaching activity of T. ferrooxidans in sludge.     

Linking ecological and ecotoxicological techniques to support river rehabilitation

Human activities in river catchments interfere with natural fluxes of water and materials. Diffuse inputs and point-sources of toxicants have modified the ecological state of riverine communities considerably, and sanitation schemes are now under development for various rivers. To improve analysis, monitoring and prospecting the role of toxicants in river ecosystems a review of the available methods is undertaken. Ecotoxicological techniques are discussed in relation to basic ecological principles that are thought to regulate the functioning of communities. The response to toxicants among species is highly diverse and therefore the choice of test species (e.g. of typical riverine insects as caddisflies or mayflies) is critical, as it is the use of test-batteries. Long-term exposure may lead to developmental disturbances that may be assessed through morphometric techniques like analysis of asymmetry. Multi-generation exposure, although rarely studied, provides a useful insight into the genetic consequences of pollution. Selection for tolerant species or varieties has been experimentally assessed for smaller organisms such as insects, micro-algae, and bacteria. There is also perspective for multivariate analysis of species distribution in relation to pollutant exposure. Furthermore, a system approach to benthic ecology and sediment testing is needed. Such an approach reflects the strong linkage of ecological and ecotoxicological processes. Toxicants are transformed by biological activity; in some cases this alleviates toxicant stress, but in other cases degradation products are toxic as well. The risk of transformation to mutagenic products in the environment is indicated. The re-assessment of some of the classical ecotoxicological techniques is needed to adequately fulfil the needs of ecological recovery programs. To this purpose integration of ecotoxicological and ecological tools is needed.     

鼠伤寒沙门氏菌的紫外灭活及光复活抑制的研究

研究了鼠伤寒沙门氏菌的紫外失活动力学、在日光灯下的光复活现象以及氯对其光复活的抑制。结果表明,鼠伤寒沙门氏菌的紫外失活动力学曲线分为滞后区、一级动力学区、拖尾区三阶段,在PBS中的一级动力学失活速率常数为0.9041 cm2/mJ。而紫外灭活后的鼠伤寒沙门氏菌在日光灯下存在光复活。当紫外剂量为10 mJ/cm2时,鼠伤寒沙门氏菌在日光灯下照射3 h内发生明显的光复活,浓度从8.6×103CFU/mL增加到4.1×106 CFU/mL;但是在紫外消毒后,投加1 mg/L的氯可以有效抑制该细菌的光复活,投加2 mg/L的氯可以在10 min内全部灭活。因此,紫外-氯联合消毒能够有效的抑制鼠伤寒沙门氏菌细菌光复活,使其得到高效灭活。     

Enhanced phytoextraction of Pb and other metals from artificially contaminated soils through the combined application of EDTA and EDDS

Chemically enhanced phytoextraction is achieved by the application of chelates to soils. Using pot experiments, the effect of the combined application of EDTA and EDDS on the uptake of Cu, Pb, Zn and Cd by Zea mays L. was studied. Among the tested application ratios of 1:1, 1:2, and 2:1 (EDTA/EDDS), 2:1 of EDTA:EDDS was the most efficient ratio for increasing the concentrations of Cu, Pb, Zn and Cd in the shoots. The combined application of 3.33 mmol kg(-1) soil of EDTA+1.67 mmol kg(-1) soil of EDDS produced 650 mg kg(-1) of Pb in the shoots, which was 2.4 and 5.9 times the concentration of Pb in the shoots treated with 5 mmol kg(-1) of EDTA and EDDS alone, respectively. The total phytoextraction of Pb reached 1710 microg kg(-1) soil, which was 2.1 and 6.1 times the total Pb from 5 mmol kg(-1) EDTA and EDDS alone, respectively. The combined application of EDTA and EDDS also significantly increased the translocation of Pb from the roots to the shoots. The mechanism of enhancing the phytoextraction of Pb by the combined application of EDTA+EDDS did not involve a change in the pH of the soil. The increase in the phytoextraction of Pb by the shoots of Z. mays L. was more pronounced than the increase of Pb in the soil solution with the combined application of EDTA and EDDS. It was thought that the major role of EDDS might be to increase the uptake and translocation of Pb from the roots to the shoots of plants.